| 摘要 |
PROBLEM TO BE SOLVED: To provide a medical syringe in which a piston does not cause creep deformation even when the piston is charged inside an injection cylinder for a long period to prevent trouble such as reduction in sealing performance of the syringe, liquid medicine leakage or the like accompanying the creep deformation.SOLUTION: In a medical syringe 1, a cylinder body 21 is formed in a nearly cylindrical shape having a small inside diameter part 24 on the tip side, and having a large inside diameter part 25 on the rear end side. A piston 3 is made of a flexible material and is formed in a larger diameter than the inside diameter of the small inside diameter part 24 of the cylinder body 21, and a peripheral part of the piston 3 can be brought into pressure-contact with the inner circumferential face of the small inside diameter part 24 of the cylinder body 21 and is formed in the outside diameter equal to or less than the inside diameter of the large inside diameter part 25 of the cylinder body 21. A plunger rod 4 is held in the center of the cylinder body 21 in a state that the plunger rod 4 is inserted in a rod insertion part of a plunger rod holder 5, and the medical syringe 1 can hold the piston 3 in the large inside diameter part 25 of the cylinder body 21 in a loosely fitting state. |
